Since March 2013, 481 people from 25 states and Puerto Rico have been infected with seven strains of Salmonella Heidelberg "likely related to Foster Farms chicken," according to the CDC. Of the cases, 38 percent had to be hospitalized, but there have been no deaths related to the outbreak.

About 75 percent of those falling ill to Salmonella Heidelberg infections are California residents.

"It raises concern that this outbreak may not be over," Robert Tauxe, the CDC's deputy director for the division of food-borne, waterborne and environmental diseases, told the Los Angeles Times Monday.

The U.S. Department of Agriculture alerted the public of salmonella-infected Foster Farms chickens last October; three of the company's processing plants in central California had been affected. Federal inspectors went on to find insanitary conditions at the plants.

In a statement on its website Monday, Foster Farms said the company has "implemented a multifaceted Salmonella control program that has reduced the prevalence of Salmonella at the parts level to less than 10 percent" and that its facilities are performing "far better than the industry average."

"We are on the right track, and have made outstanding progress," Ron Foster, Foster Farms chief executive officer, said in a statement. "Millions of consumers continue to enjoy Foster Farms poultry products each day, and we want to ensure that they have the safest, healthiest experience."

Since March 2013, 481 people from 25 states and Puerto Rico have been infected with seven strains of Salmonella Heidelberg "likely related to Foster Farms chicken," according to the CDC. Of the cases, 38 percent had to be hospitalized, but there have been no deaths related to the outbreak.